The major goal fr the final year is to identify central cells that control locomotory behavior and ineract with peripheral circuits that cntain the motor neurones for locomotion. The preparation used is a unique one, Notoplana acticola, an animal that possesses one of the smallest, most primitive brains available. The nervous system is a plexus. Both the brain and plexus are amenable to dissection and electrophysiological investigations. The part of the brain controlling locomotion will be identified by recording from the surface of the brain during locomotion. Cells in the actiie region will also be localized by ablating different regions of the brain and examining the behavior. Once the correct cells have been identified they will be examined using intracellular recording techniques. The morphology and connectivity of the cells will be investigated by filling individualneurones with fluorescent dyes. The procedures for doing this have already been worked out for this preparation. Activity of individual cells will be monitored during the initiation of locomotory behavior. We will also attempt to locate the nerve cells in the peripheral plexus that are active during behavior and examine the way that these are influenced by activity of the central cells. Koopowitz, H., Bernardo, K., Keenan, L. (1979) Primitive nervous systems; Electrical activity in ventral nerve cords of the flatworm, Notoplaa acticola. J. Neurbiology, 10: 367-381. Koopowitz, H., Keenan, L., Bernardo, K. (1979) Primitive nervous systems: Electrophysiology of inhibitory events in flatworm nerve cords. J. Neurobiology, 10: 383-395.